Lettuce line RX06462133

ABSTRACT

The invention provides seed and plants of the lettuce line designated RX06462133. The invention thus relates to the plants, seeds and tissue cultures of lettuce line RX06462133, and to methods for producing a lettuce plant produced by crossing a plant of lettuce line RX06462133 with itself or with another lettuce plant, such as a plant of another line. The invention further relates to seeds and plants produced by such crossing. The invention further relates to parts of a plant of lettuce line RX06462133, including the gametes of such plants.

FIELD OF THE INVENTION

The present invention relates to the field of plant breeding and, morespecifically, to the development of lettuce line RX06462133.

BACKGROUND OF THE INVENTION

The goal of vegetable breeding is to combine various desirable traits ina single variety/hybrid. Such desirable traits may include greateryield, resistance to insects or pests, tolerance to heat and drought,better agronomic quality, higher nutritional value, growth rate andfruit properties.

Breeding techniques take advantage of a plant's method of pollination.There are two general methods of pollination: a plant self-pollinates ifpollen from one flower is transferred to the same or another flower ofthe same plant or plant variety. A plant cross-pollinates if pollencomes to it from a flower of a different plant variety.

Plants that have been self-pollinated and selected for type over manygenerations become homozygous at almost all gene loci and produce auniform population of true breeding progeny, a homozygous plant. A crossbetween two such homozygous plants of different varieties produces auniform population of hybrid plants that are heterozygous for many geneloci. Conversely, a cross of two plants each heterozygous at a number ofloci produces a population of hybrid plants that differ genetically andare not uniform. The resulting non-uniformity makes performanceunpredictable.

The development of uniform varieties requires the development ofhomozygous inbred plants, the crossing of these inbred plants, and theevaluation of the crosses. Pedigree breeding and recurrent selection areexamples of breeding methods that have been used to develop inbredplants from breeding populations. Those breeding methods combine thegenetic backgrounds from two or more plants or various other broad-basedsources into breeding pools from which new lines are developed byselfing and selection of desired phenotypes. The new lines are evaluatedto determine which of those have commercial potential.

One crop species which has been subject to such breeding programs and isof particular value is lettuce. Lettuce, Lactuca sativa, is a temperateannual or biennial plant most often grown as a leaf vegetable. Lettucebelongs to the family Asteraceae (or Compositae). Other members of thisfamily include endive, chicory, artichoke, sunflower and safflower. Itis closely related to common wild lettuce or prickly lettuce (L.serriola) and less closely related to two other wild lettuces (L.saligna and L. virosa). Lettuce and sunflower are the best geneticallycharacterized members of this family. Four principal types of lettuceinclude crisphead (mostly iceberg), romaine (cos), leaf and butterhead.Each of these basic groups is comprised of numerous cultivars, eachcharacterized by its own particular morphology, disease resistance andcultural adaptations. These types vary in size, shape, texture, color,nutritional value and taste. The principal nutrients are vitamins A andC and calcium, and the percentage water content in lettuce is high(e.g., 93-96%).

A lettuce plant has a short stem initially, but when it blooms, the stemlengthens and branches, producing many flower heads that look like thoseof dandelions, but smaller. This is called bolting. When grown to eat,lettuce is harvested before it bolts. In the United States, more than90% of the nation's lettuce is grown in California and Arizona. InCalifornia, variations in temperature in the regions where lettuce isgrown allows for a continuous supply of lettuce year-round, although thegreatest supply is from May through October.

Lettuce is a diploid species with 2N=18 chromosomes and naturallyself-pollinates. The self-pollination feature leads to inbred lines thatare uniform and vigorous, and therefore exhibit extensive genetichomozygosity. Virtually all commercial cultivars in use today are inbredlines. Hybrid development has not been pursued with much interest due tothe tedious nature of manual crossing and low seed production per cross.Furthermore, there is no consistent large-scale pollen movement byinsects or wind.

The principal breeding mechanisms are pedigree breeding andbackcrossing, but straight selection of desirable plants within acultivar is also practiced to slightly modify the cultivar. Choice ofbreeding or selection methods depends on, for example, the mode of plantreproduction, the heritability of the trait(s) being improved and thetype of cultivar used commercially. Since the flowers of lettuce aredelicate and emasculation is tedious and difficult, lettuce breederstypically wait until the flowers open and then wash away the self-pollenprior to crossing.

While breeding efforts to date have provided a number of useful lettucelines with beneficial traits, there remains a great need in the art fornew lines with further improved traits. Such plants would benefitfarmers and consumers alike by improving crop yields and/or quality.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a lettuce plant of theline designated RX06462133. Also provided are lettuce plants having allthe physiological and morphological characteristics of the lettuce linedesignated RX06462133. Parts of the lettuce plant of the presentinvention are also provided, for example, including pollen, an ovule anda cell of the plant.

The invention also concerns seed of lettuce line RX06462133. The lettuceseed of the invention may be provided as an essentially homogeneouspopulation of lettuce seed of the line designated RX06462133.Essentially homogeneous populations of seed are generally free fromsubstantial numbers of other seed. Therefore, seed of line RX06462133may be defined as forming at least about 97% of the total seed,including at least about 98%, 99%, or more of the seed. The populationof lettuce seed may be particularly defined as being essentially freefrom hybrid seed. The seed population may be separately grown to providean essentially homogeneous population of lettuce plants designatedRX06462133.

In another aspect of the invention, a plant of lettuce line RX06462133comprising an added heritable trait is provided. The heritable trait maycomprise a genetic locus that is a dominant or recessive allele. In oneembodiment of the invention, a plant of lettuce line RX06462133 isdefined as comprising a single locus conversion. In specific embodimentsof the invention, an added genetic locus confers one or more traits suchas, for example, herbicide tolerance, insect resistance, diseaseresistance, and modified carbohydrate metabolism. The trait may be, forexample, conferred by a naturally occurring gene introduced into thegenome of the line by backcrossing, a natural or induced mutation, or atransgene introduced through genetic transformation techniques into theplant or a progenitor of any previous generation thereof. Whenintroduced through transformation, a genetic locus may comprise one ormore transgenes integrated at a single chromosomal location.

In another aspect of the invention, a tissue culture of regenerablecells of a plant of line RX06462133 is provided. The tissue culture willpreferably be capable of regenerating plants capable of expressing allof the physiological and morphological characteristics of the line, andof regenerating plants having substantially the same genotype as otherplants of the line. Examples of some of the physiological andmorphological characteristics of the line RX06462133 include thosetraits set forth in the tables herein. The regenerable cells in suchtissue cultures may be derived, for example, from embryos, meristems,cotyledons, pollen, leaves, anthers, roots, root tips, pistil, flower,seed and stalks. Still further, the present invention provides lettuceplants regenerated from a tissue culture of the invention, the plantshaving all the physiological and morphological characteristics of lineRX06462133.

In yet another aspect of the invention, processes are provided forproducing lettuce seeds and plants, which processes generally comprisecrossing a first parent lettuce plant with a second parent lettuceplant, wherein at least one of the first or second parent lettuce plantsis a plant of the line designated RX06462133. These processes may befurther exemplified as processes for preparing hybrid lettuce seed orplants, wherein a first lettuce plant is crossed with a second lettuceplant of a different, distinct line to provide a hybrid that has, as oneof its parents, the lettuce plant line RX06462133. In these processes,crossing will result in the production of seed. The seed productionoccurs regardless of whether the seed is collected or not.

In one embodiment of the invention, the first step in “crossing”comprises planting seeds of a first and second parent lettuce plant,often in proximity so that pollination will occur for example, mediatedby insect vectors. Alternatively, pollen can be transferred manually.Where the plant is self-pollinated, pollination may occur without theneed for direct human intervention other than plant cultivation.

A second step may comprise cultivating or growing the seeds of first andsecond parent lettuce plants into plants that bear flowers. A third stepmay comprise preventing self-pollination of the plants, such as byemasculating the male portions of flowers, (i.e., treating ormanipulating the flowers to produce an emasculated parent lettuceplant). Self-incompatibility systems may also be used in some hybridcrops for the same purpose. Self-incompatible plants still shed viablepollen and can pollinate plants of other varieties but are incapable ofpollinating themselves or other plants of the same line.

A fourth step for a hybrid cross may comprise cross-pollination betweenthe first and second parent lettuce plants. Yet another step comprisesharvesting the seeds from at least one of the parent lettuce plants. Theharvested seed can be grown to produce a lettuce plant or hybrid lettuceplant.

The present invention also provides the lettuce seeds and plantsproduced by a process that comprises crossing a first parent lettuceplant with a second parent lettuce plant, wherein at least one of thefirst or second parent lettuce plants is a plant of the line designatedRX06462133. In one embodiment of the invention, lettuce seed and plantsproduced by the process are first generation (F₁) hybrid lettuce seedand plants produced by crossing a plant in accordance with the inventionwith another, distinct plant. The present invention further contemplatesplant parts of such an F₁ hybrid lettuce plant, and methods of usethereof. Therefore, certain exemplary embodiments of the inventionprovide an F₁ hybrid lettuce plant and seed thereof.

In still yet another aspect of the invention, the genetic complement ofthe lettuce plant line designated RX06462133 is provided. The phrase“genetic complement” is used to refer to the aggregate of nucleotidesequences, the expression of which sequences defines the phenotype of,in the present case, a lettuce plant, or a cell or tissue of that plant.A genetic complement thus represents the genetic makeup of a cell,tissue or plant, and a hybrid genetic complement represents the geneticmake up of a hybrid cell, tissue or plant. The invention thus provideslettuce plant cells that have a genetic complement in accordance withthe lettuce plant cells disclosed herein, and plants, seeds and plantscontaining such cells.

Plant genetic complements may be assessed by genetic marker profiles,and by the expression of phenotypic traits that are characteristic ofthe expression of the genetic complement, e.g., isozyme typing profiles.It is understood that line RX06462133 or a first generation progenythereof could be identified by any of the many well known techniquessuch as, for example, Simple Sequence Length Polymorphisms (SSLPs)(Williams et al., 1990), Randomly Amplified Polymorphic DNAs (RAPDs),DNA Amplification Fingerprinting (DAF), Sequence Characterized AmplifiedRegions (SCARs), Arbitrary Primed Polymerase Chain Reaction (AP-PCR),Amplified Fragment Length Polymorphisms (AFLPs) (EP 534 858,specifically incorporated herein by reference in its entirety), andSingle Nucleotide Polymorphisms (SNPs) (Wang et al., 1998).

In still yet another aspect, the present invention provides hybridgenetic complements, as represented by lettuce plant cells, tissues,plants, and seeds, formed by the combination of a haploid geneticcomplement of a lettuce plant of the invention with a haploid geneticcomplement of a second lettuce plant, preferably, another, distinctlettuce plant. In another aspect, the present invention provides alettuce plant regenerated from a tissue culture that comprises a hybridgenetic complement of this invention.

In still yet another aspect, the invention provides a method ofdetermining the genotype of a plant of lettuce line RX06462133comprising detecting in the genome of the plant at least a firstpolymorphism. The method may, in certain embodiments, comprise detectinga plurality of polymorphisms in the genome of the plant. The method mayfurther comprise storing the results of the step of detecting theplurality of polymorphisms on a computer readable medium. The inventionfurther provides a computer readable medium produced by such a method.

In still yet another aspect, the present invention provides a method ofproducing a plant derived from line RX06462133, the method comprisingthe steps of: (a) preparing a progeny plant derived from lineRX06462133, wherein said preparing comprises crossing a plant of theline RX06462133 with a second plant; and (b) crossing the progeny plantwith itself or a second plant to produce a seed of a progeny plant of asubsequent generation. In further embodiments, the method mayadditionally comprise: (c) growing a progeny plant of a subsequentgeneration from said seed of a progeny plant of a subsequent generationand crossing the progeny plant of a subsequent generation with itself ora second plant; and repeating the steps for an additional 3-10generations to produce a plant derived from line RX06462133. The plantderived from line RX06462133 may be an inbred line, and theaforementioned repeated crossing steps may be defined as comprisingsufficient inbreeding to produce the inbred line. In the method, it maybe desirable to select particular plants resulting from step (c) forcontinued crossing according to steps (b) and (c). By selecting plantshaving one or more desirable traits, a plant derived from lineRX06462133 is obtained which possesses some of the desirable traits ofthe line as well as potentially other selected traits.

In certain embodiments, the present invention provides a method ofproducing lettuce comprising: (a) obtaining a plant of lettuce lineRX06462133, wherein the plant has been cultivated to maturity, and (b)collecting lettuce from the plant.

Any embodiment discussed herein with respect to one aspect of theinvention applies to other aspects of the invention as well, unlessspecifically noted.

The term “about” is used to indicate that a value includes the standarddeviation of error for the device or method being employed to determinethe value. The use of the term “or” in the claims is used to mean“and/or” unless explicitly indicated to refer to alternatives only orthe alternatives are mutually exclusive, although the disclosuresupports a definition that refers to only alternatives and to “and/or.”When used in conjunction with the word “comprising” or other openlanguage in the claims, the words “a” and “an” denote “one or more,”unless specifically noted. The terms “comprise,” “have” and “include”are open-ended linking verbs. Any forms or tenses of one or more ofthese verbs, such as “comprises,” “comprising,” “has,” “having,”“includes” and “including,” are also open-ended. For example, any methodthat “comprises,” “has” or “includes” one or more steps is not limitedto possessing only those one or more steps and also covers otherunlisted steps. Similarly, any plant that “comprises,” “has” or“includes” one or more traits is not limited to possessing only thoseone or more traits and covers other unlisted traits.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description. It should beunderstood, however, that the detailed description and any specificexamples provided, while indicating specific embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides methods and compositions relating to plants,seeds and derivatives of lettuce line RX06462133. This line showsuniformity and stability within the limits of environmental influencefor the traits described hereinafter. Lettuce line RX06462133 providessufficient seed yield. By crossing with a distinct second plant, uniformF1 hybrid progeny can be obtained.

Line RX06462133 exhibits a number of improved traits includingresistance to Bremia lactucae races B1:1 to B1:26; resistance to lettuceaphid Nasonovia ribis nigri biotype 0 (Nr:0); and resistance to LettuceMosaic Virus common strain (LMV:0). The development of the line can besummarized as follows.

A. Origin and Breeding History of Lettuce Line RX06462133

Lettuce cultivar RX06462133 was developed from an initial cross betweena butterhead lettuce breeding line from Seminis named 20025637, whichpossessed resistance to Bremia lactucae race B1:25, resistance to thelettuce aphid Nasonovia ribis nigri biotype 0 (Nr:0) and resistance toLettuce Mosaic Virus common strain (LMV:0), as the male parent; and aNunhems lettuce variety named SYLVESTA, a butterhead lettuce type,without resistance to Bremia lactucae race B1:25 and with resistance toNasonovia ribis nigri biotype 0 and Lettuce Mosaic Virus common strain(LMV:0), as a female parent. The breeding history can be summarized asfollows:

SELECTION YEAR GENERATION/PEDIGREE #LINES CRITERIA 1 F1 Sylvesta x20025637 1 F2 Sylvesta x 20025637 3 2 F3 Sylvesta x 20025637 13resistance to B1:20 3 F4 Sylvesta x 20025637 25 resistance to B1:20,plant type and uniformity 3 F5 Sylvesta x 20025637 8 uniformity, planttype

A breeding line designated 20062133 was identified as the most uniformline with resistance to Bremia lactucae B1:20 and to Nasonovia ribisnigri biotype 0, and was selected as a seed source for lettuce varietyRX06462133. A total of 40,000 plants from bulked seed of the breedingline were tested all over Europe in spring, summer, autumn and wintergrowing conditions and compared for stability and uniformity of thevariety. In all trials the bulked seed looked uniform and stable.Neither off-types nor genetic variation were detected during thosetrials.

B. Physiological and Morphological Characteristics of Lettuce LineRX06462133

In accordance with one aspect of the present invention, there isprovided a plant having the physiological and morphologicalcharacteristics of lettuce line RX06462133. A description of thephysiological and morphological characteristics of lettuce lineRX06462133 is presented in Table 1.

TABLE 1 Physiological and Morphological Characteristics of LineRX06462133 Comparison Variety Comparison Variety-Dark CHARACTERISTICRX06462133 Variety-Mafalda Green Boston 1. Type Butterhead ButterheadButterhead 2. Seed Color white (US = Silver white (US = Silver white (US= Silver Gray) Gray) Gray) [TG = Verpia] [TG = Verpia] [TG = Verpia]Light dormancy light not required light not required light not requiredHeat dormancy susceptible susceptible susceptible 3. Seedlinganthocyanin absent (Verpia) absent (Verpia) absent (Verpia) colorationsize of cotyledon medium medium medium (fully developed) (Expresse)(Expresse) (Expresse) shape of cotyledon medium elliptic medium ellipticbroad elliptic (Frisette) (Frisette) (Fiorella, Sunrise) 4. Leaf shapeof cotyledons intermediate intermediate intermediate shape of fourthleaf elongated elongated elongated length/width index of 14.5  14  14.4fourth leaf (length/ width × 10) apical margin finely dentatecrenate/gnawed finely dentate (cotyledon to 4^(th) leaf stage) basalmargin moderately dentate moderately dentate moderately dentate(cotyledon to 4^(th) leaf stage) undulation (cotyledon medium mediumslight to 4^(th) leaf stage green color medium green light green mediumgreen (cotyledon to 4^(th) leaf stage) anthocyanin absent absent absentdistribution (cotyledon to 4^(th) leaf stage) rolling (cotyledon topresent absent present 4^(th) leaf stage) cupping (cotyledon to uncuppeduncupped uncupped 4^(th) leaf stage) reflexing (cotyledon apical marginapical margin apical margin to 4^(th) leaf stage) attitude at 10-12 leafsemi-erect (Great semi-erect (Great prostrate (Unicum, stage Lakes 118,Soraya) Lakes 118, Soraya) Vanguard 75) leaf blade: division at entire(Fiorella, entire (Fiorella, entire (Fiorella, 10-12 leaf stage Sunrise)Sunrise) Sunrise) leaf blade: incisions absent (Verpia) absent (Verpia)absent (Verpia) of margin on apical part leaf blade: depth ofabsent/shallow absent/shallow absent/shallow incisions on margin (US:Dark Green (US: Dark Green (US: Dark Green on apical part Boston) [TG:Boston) [TG: Boston) [TG: (harvest mature outer Pentared, Unicum]Pentared, Unicum] Pentared, Unicum] leaves) leaf blade: venation notflabellate not flabellate not flabellate (Donatella, Verpia, (Donatella,Verpia, (Donatella, Verpia, Xanadu) Xanadu) Xanadu) mature leaves:entire (Dark Green entire (Dark Green entire (Dark Green indentationfinest Boston) Boston) Boston) divisions of the margin (harvest matureouter leaves) leaf blade: degree of absent/slight/veryabsent/slight/very absent/slight/very undulation of apical weak (US:Dark weak (US: Dark weak (US: Dark margin (harvest Green Boston) [TG:Green Boston) [TG: Green Boston) [TG: mature outer leaves) Dustin,Manfred] Dustin, Manfred] Dustin, Manfred] green color (harvest mediumgreen light green medium green mature outer leaves) (Great Lakes)(Minetto) (Great Lakes) hue of green color of absent (Donatello, absent(Donatello, greyish (Celtuce, outer leaves Verpia) Verpia) Du bonjardinier) intensity of color of medium medium dark outer leavesanthocyanin absent [TG: absent [TG: absent [TG: coloration (harvestFiorella, Sunrise] Fiorella, Sunrise] Fiorella, Sunrise] mature outerleaves) size (harvest mature medium medium medium outer leaves)glossiness of upper absent or very absent or very dull/weak (US: side(harvest mature weak [TG: Divina, weak [TG: Divina, Vanguard) [TG: outerleaves) Du bon jardinier] Du bon jardinier] Elsa, Fiorella] blistering(harvest absent/slight or absent/slight or weak [TG: mature outerleaves) very weak (US: very weak (US: Fiorella, Minas] Salinas) [TG:Salinas) [TG: Donia, Frillblond] Donia, Frillblond] size of blistersmedium (Dustin, Sunrise) thickness (harvest medium (Dustin, medium(Dustin, medium (Dustin, mature outer leaves) Sunrise) Sunrise) Sunrise)trichomes (harvest absent (smooth) absent (smooth) absent (smooth)mature outer leaves) attitude at harvest semi-erect semi-erectsemi-erect maturity (outer leaves (Amelia, Toronto (Amelia, Toronto(Amelia, Toronto from head lettuce or adult leaves from cutting and stemlettuce) shape transverse broad transverse broad transverse broadelliptic (Commodore, elliptic (Commodore, elliptic (Commodore, Fiorella)Fiorella) Fiorella) shape of tip rounded (Blonde rounded (Blonde rounded(Blonde Maraîchère, Maserati) Maraîchère, Maserati) Maraîchère,Maserati) 5. Plant spread of frame  27 cm  29 cm  27 cm leaves diametermedium medium large medium (Clarion, Verpia) (Clarion, Verpia) height(flowering medium medium medium plant) (Samourai) (Samourai) (Samourai)fasciation (at absent (Calmar, present (Gotte absent (Calmar, floweringstage) Romance) Jaune d'or) Romance) intensity of fasciation very weak(Gotte à (flowering plant) graine blanche) head formation closed head/closed head/ closed head/ overlapping overlapping overlapping (Kelvin,Sunrise) (Kelvin, Sunrise) (Kelvin, Sunrise) head: degree of mediummedium medium overlapping of upper (Augusta, (Augusta, (Augusta, part ofplant (varieties Fiorella) Fiorella) Fiorella) with closed headformation only) head diameter  13 cm  14 cm  13 cm (market trimmed withsingle cap leaf) head shape spherical spherical spherical head shape incircular (Passe circular (Passe circular (Passe longitudinal sectionPartout, Verpia) Partout, Verpia) Partout, Verpia) head size (class)medium medium (Fiorella, medium (Fiorella, (Fiorella, Soraya) Soraya)Soraya) heads per carton  24  24  24 head weight 511 gms 446 gms 496 gmshead firmness/density medium (Blonde medium (Blonde medium (Blondemaraîchère, maraîchère, maraîchère, 6. Butt shape flat flat flat midribmoderately raised moderately raised moderately raised 7. Core diameterat base of  29 mm  25 mm  30 mm head ratio of head diameter/   4.4   5.4  4.4 core diameter core height from base  40 mm  34 mm  37 mm of headto apex 8. Bolting first water date Mar. 14, 2009 Mar. 14, 2009 Mar. 14,2009 number of days from  78  75  72 first water date to seed stalkemergence (summer conditions) bolting class medium medium rapid time ofbeginning of medium (Carelia) medium (Carelia) early medium boltingunder long day conditions height of mature seed 105 cm  93 cm  93 cmstalk spread of bolter plant  52 cm  50 cm  58 cm (at widest point)bolter leaves straight straight straight margin dentate dentate dentatecolor medium green medium green dark green bolter habit: terminalpresent present present inflorescence bolter habit: lateral presentpresent present shoots bolter habit: basal present absent present sideshoots axillary sprouting medium medium strong (Riva) time of harvestmedium medium (Newton) medium (Newton) maturity (Newton) *These aretypical values. Values may vary due to environment. Other values thatare substantially equivalent are also within the scope of the invention.

Line RX06462133 has been self-pollinated and planted for a number ofgenerations to produce the homozygosity and phenotypic stability to makethis line useful in commercial seed production. No variant traits havebeen observed or are expected for this line.

Lettuce line RX06462133, being substantially homozygous, can bereproduced by planting seeds of the line, growing the resulting lettuceplant under self-pollinating or sib-pollinating conditions andharvesting the resulting seeds using techniques familiar to one of skillin the art.

C. Breeding Lettuce Line RX06462133

One aspect of the current invention concerns methods for crossing thelettuce line RX06462133 with itself or a second plant and the seeds andplants produced by such methods. These methods can be used forpropagation of line RX06462133, or can be used to produce hybrid lettuceseeds and the plants grown therefrom. Hybrid seeds are produced bycrossing line RX06462133 with second lettuce parent line.

The development of new varieties using one or more starting varieties iswell known in the art. In accordance with the invention, novel varietiesmay be created by crossing line RX06462133 followed by multiplegenerations of breeding according to such well known methods. Newvarieties may be created by crossing with any second plant. In selectingsuch a second plant to cross for the purpose of developing novel lines,it may be desired to choose those plants which either themselves exhibitone or more selected desirable characteristics or which exhibit thedesired characteristic(s) when in hybrid combination. Once initialcrosses have been made, inbreeding and selection take place to producenew varieties. For development of a uniform line, often five or moregenerations of selfing and selection are involved.

Uniform lines of new varieties may also be developed by way ofdouble-haploids. This technique allows the creation of true breedinglines without the need for multiple generations of selfing andselection. In this manner true breeding lines can be produced in aslittle as one generation. Haploid embryos may be produced frommicrospores, pollen, anther cultures, or ovary cultures. The haploidembryos may then be doubled autonomously, or by chemical treatments(e.g. colchicine treatment). Alternatively, haploid embryos may be growninto haploid plants and treated to induce chromosome doubling. In eithercase, fertile homozygous plants are obtained. In accordance with theinvention, any of such techniques may be used in connection with lineRX06462133 and progeny thereof to achieve a homozygous line.

New varieties may be created, for example, by crossing line RX06462133with any second plant and selection of progeny in various generationsand/or by doubled haploid technology. In choosing a second plant tocross for the purpose of developing novel lines, it may be desired tochoose those plants which either themselves exhibit one or more selecteddesirable characteristics or which exhibit the desired characteristic(s)in progeny. After one or more lines are crossed, true-breeding lines maybe developed.

Backcrossing can also be used to improve an inbred plant. Backcrossingtransfers a specific desirable trait from one inbred or non-inbredsource to an inbred that lacks that trait. This can be accomplished, forexample, by first crossing a superior inbred (A) (recurrent parent) to adonor inbred (non-recurrent parent), which carries the appropriate locusor loci for the trait in question. The progeny of this cross are thenmated back to the superior recurrent parent (A) followed by selection inthe resultant progeny for the desired trait to be transferred from thenon-recurrent parent. After five or more backcross generations withselection for the desired trait, the progeny are heterozygous for locicontrolling the characteristic being transferred, but are like thesuperior parent for most or almost all other loci. The last backcrossgeneration would be selfed to give pure breeding progeny for the traitbeing transferred.

The line of the present invention is particularly well suited for thedevelopment of new lines based on the elite nature of the geneticbackground of the line. In selecting a second plant to cross withRX06462133 for the purpose of developing novel lettuce lines, it willtypically be preferred to choose those plants which either themselvesexhibit one or more selected desirable characteristics or which exhibitthe desired characteristic(s) when in hybrid combination.

D. Performance Characteristics

As described above, line RX06462133 exhibits desirable agronomic traits,including resistance to Bremia lactucae races B1:1 to B1:26; resistanceto lettuce aphid Nasonovia ribis nigri biotype 0 (Nr:0); and resistanceto Lettuce Mosaic Virus common strain (LMV:0). These and otherperformance characteristics of the line were the subject of an objectiveanalysis of the performance traits of the line relative to other lines.The results of the analysis are presented below.

TABLE 2 Performance Characteristics For Line RX06462133 Resistance toDowny Mildew Resistance to Downy Mildew (Bremia lactucae) Race VII(Bremia lactucae) Race VIII RX06462133 resistant resistant SYLVES TAsusceptible susceptible

E. Further Embodiments of the Invention

In specific embodiments, the invention provides plants modified toinclude at least a first desired heritable trait. Such plants may, inone embodiment, be developed by a plant breeding technique calledbackcrossing, wherein essentially all of the desired morphological andphysiological characteristics of a variety are recovered in addition toa genetic locus transferred into the plant via the backcrossingtechnique. The term single locus converted plant as used herein refersto those lettuce plants which are developed by a plant breedingtechnique called backcrossing, wherein essentially all of the desiredmorphological and physiological characteristics of a variety arerecovered in addition to the single locus transferred into the varietyvia the backcrossing technique.

Backcrossing methods can be used with the present invention to improveor introduce a characteristic into the present variety. The parentallettuce plant which contributes the locus for the desired characteristicis termed the nonrecurrent or donor parent. This terminology refers tothe fact that the nonrecurrent parent is used one time in the backcrossprotocol and therefore does not recur. The parental lettuce plant towhich the locus or loci from the nonrecurrent parent are transferred isknown as the recurrent parent as it is used for several rounds in thebackcrossing protocol.

In a typical backcross protocol, the original variety of interest(recurrent parent) is crossed to a second variety (nonrecurrent parent)that carries the single locus of interest to be transferred. Theresulting progeny from this cross are then crossed again to therecurrent parent and the process is repeated until a lettuce plant isobtained wherein essentially all of the desired morphological andphysiological characteristics of the recurrent parent are recovered inthe converted plant, in addition to the single transferred locus fromthe nonrecurrent parent.

The selection of a suitable recurrent parent is an important step for asuccessful backcrossing procedure. The goal of a backcross protocol isto alter or substitute a single trait or characteristic in the originalvariety. To accomplish this, a single locus of the recurrent variety ismodified or substituted with the desired locus from the nonrecurrentparent, while retaining essentially all of the rest of the desiredgenetic, and therefore the desired physiological and morphologicalconstitution of the original variety. The choice of the particularnonrecurrent parent will depend on the purpose of the backcross; one ofthe major purposes is to add some commercially desirable trait to theplant. The exact backcrossing protocol will depend on the characteristicor trait being altered to determine an appropriate testing protocol.Although backcrossing methods are simplified when the characteristicbeing transferred is a dominant allele, a recessive allele may also betransferred. In this instance it may be necessary to introduce a test ofthe progeny to determine if the desired characteristic has beensuccessfully transferred.

In one embodiment, progeny lettuce plants of a backcross in whichRX06462133 is the recurrent parent comprise (i) the desired trait fromthe non-recurrent parent and (ii) all of the physiological andmorphological characteristics of lettuce line RX06462133 as determinedat the 5% significance level when grown in the same environmentalconditions.

Lettuce varieties can also be developed from more than two parents. Thetechnique, known as modified backcrossing, uses different recurrentparents during the backcrossing. Modified backcrossing may be used toreplace the original recurrent parent with a variety having certain moredesirable characteristics or multiple parents may be used to obtaindifferent desirable characteristics from each.

Many single locus traits have been identified that are not regularlyselected for in the development of a new inbred but that can be improvedby backcrossing techniques. Single locus traits may or may not betransgenic; examples of these traits include, but are not limited to,male sterility, herbicide resistance, resistance to bacterial, fungal,or viral disease, insect resistance, restoration of male fertility,modified fatty acid or carbohydrate metabolism, and enhanced nutritionalquality. These comprise genes generally inherited through the nucleus.

Direct selection may be applied where the single locus acts as adominant trait. An example of a dominant trait is the downy mildewresistance trait. For this selection process, the progeny of the initialcross are sprayed with downy mildew spores prior to the backcrossing.The spraying eliminates any plants which do not have the desired downymildew resistance characteristic, and only those plants which have thedowny mildew resistance gene are used in the subsequent backcross. Thisprocess is then repeated for all additional backcross generations.

Selection of lettuce plants for breeding is not necessarily dependent onthe phenotype of a plant and instead can be based on geneticinvestigations. For example, one can utilize a suitable genetic markerwhich is closely genetically linked to a trait of interest. One of thesemarkers can be used to identify the presence or absence of a trait inthe offspring of a particular cross, and can be used in selection ofprogeny for continued breeding. This technique is commonly referred toas marker assisted selection. Any other type of genetic marker or otherassay which is able to identify the relative presence or absence of atrait of interest in a plant can also be useful for breeding purposes.Procedures for marker assisted selection applicable to the breeding oflettuce are well known in the art. Such methods will be of particularutility in the case of recessive traits and variable phenotypes, orwhere conventional assays may be more expensive, time consuming orotherwise disadvantageous. Types of genetic markers which could be usedin accordance with the invention include, but are not necessarilylimited to, Simple Sequence Length Polymorphisms (SSLPs) (Williams etal., 1990), Randomly Amplified Polymorphic DNAs (RAPDs), DNAAmplification Fingerprinting (DAF), Sequence Characterized AmplifiedRegions (SCARs), Arbitrary Primed Polymerase Chain Reaction (AP-PCR),Amplified Fragment Length Polymorphisms (AFLPs) (EP 534 858,specifically incorporated herein by reference in its entirety), andSingle Nucleotide Polymorphisms (SNPs) (Wang et al., 1998).

F. Plants Derived From Lettuce Line RX06462133 by Genetic Engineering

Many useful traits that can be introduced by backcrossing, as well asdirectly into a plant, are those which are introduced by genetictransformation techniques. Genetic transformation may therefore be usedto insert a selected transgene into the lettuce line of the invention ormay, alternatively, be used for the preparation of transgenes which canbe introduced by backcrossing. Methods for the transformation of plants,including lettuce, are well known to those of skill in the art.

Vectors used for the transformation of lettuce cells are not limited solong as the vector can express an inserted DNA in the cells. Forexample, vectors comprising promoters for constitutive gene expressionin lettuce cells (e.g., cauliflower mosaic virus 35S promoter) andpromoters inducible by exogenous stimuli can be used. Examples ofsuitable vectors include pBI binary vector. The “lettuce cell” intowhich the vector is to be introduced includes various forms of lettucecells, such as cultured cell suspensions, protoplasts, leaf sections,and callus.

A vector can be introduced into lettuce cells by known methods, such asthe polyethylene glycol method, polycation method, electroporation,Agrobacterium-mediated transfer, particle bombardment and direct DNAuptake by protoplasts. See, e.g., Pang et al. (1996).

To effect transformation by electroporation, one may employ eitherfriable tissues, such as a suspension culture of cells or embryogeniccallus or alternatively one may transform immature embryos or otherorganized tissue directly. In this technique, one would partiallydegrade the cell walls of the chosen cells by exposing them topectin-degrading enzymes (pectolyases) or mechanically wound tissues ina controlled manner. An example of electroporation of lettuceprotoplasts is presented in Chupeau et al. (1989).

A particularly efficient method for delivering transforming DNA segmentsto plant cells is microprojectile bombardment. In this method, particlesare coated with nucleic acids and delivered into cells by a propellingforce. Exemplary particles include those comprised of tungsten,platinum, and preferably, gold. For the bombardment, cells in suspensionare concentrated on filters or solid culture medium. Alternatively,immature embryos or other target cells may be arranged on solid culturemedium. The cells to be bombarded are positioned at an appropriatedistance below the macroprojectile stopping plate.

An illustrative embodiment of a method for delivering DNA into plantcells by acceleration is the Biolistics Particle Delivery System, whichcan be used to propel particles coated with DNA or cells through ascreen, such as a stainless steel or Nytex screen, onto a surfacecovered with target lettuce cells. The screen disperses the particles sothat they are not delivered to the recipient cells in large aggregates.It is believed that a screen intervening between the projectileapparatus and the cells to be bombarded reduces the size of projectilesaggregate and may contribute to a higher frequency of transformation byreducing the damage inflicted on the recipient cells by projectiles thatare too large.

Microprojectile bombardment techniques are widely applicable, and may beused to transform virtually any plant species. Examples involvingmicroprojectile bombardment transformation with lettuce can be found in,for example, Elliott et al. (2004) and Molinier et al. (2002).

Agrobacterium-mediated transfer is another widely applicable system forintroducing gene loci into plant cells. An advantage of the technique isthat DNA can be introduced into whole plant tissues, thereby bypassingthe need for regeneration of an intact plant from a protoplast. ModernAgrobacterium transformation vectors are capable of replication in E.coli as well as Agrobacterium, allowing for convenient manipulations(Klee et al., 1985). Moreover, recent technological advances in vectorsfor Agrobacterium-mediated gene transfer have improved the arrangementof genes and restriction sites in the vectors to facilitate theconstruction of vectors capable of expressing various polypeptide codinggenes. The vectors described have convenient multi-linker regionsflanked by a promoter and a polyadenylation site for direct expressionof inserted polypeptide coding genes. Additionally, Agrobacteriumcontaining both armed and disarmed Ti genes can be used fortransformation.

In those plant strains where Agrobacterium-mediated transformation isefficient, it is the method of choice because of the facile and definednature of the gene locus transfer. The use of Agrobacterium-mediatedplant integrating vectors to introduce DNA into plant cells is wellknown in the art (Fraley et al., 1985; U.S. Pat. No. 5,563,055). Forexample, U.S. Pat. No. 5,349,124 describes a method of transforminglettuce plant cells using Agrobacterium-mediated transformation. Byinserting a chimeric gene having a DNA coding sequence encoding for thefull-length B.t. toxin protein that expresses a protein toxic towardLepidopteran larvae, this methodology resulted in lettuce havingresistance to such insects.

Transformation of plant protoplasts also can be achieved using methodsbased on calcium phosphate precipitation, polyethylene glycol treatment,electroporation, and combinations of these treatments (see, e.g.,Potrykus et al., 1985; Omirulleh et al., 1993; Fromm et al., 1986;Uchimiya et al., 1986; Marcotte et al., 1988). Transformation of plantsand expression of foreign genetic elements is exemplified in Choi et al.(1994) and Ellul et al. (2003).

A number of promoters have utility for plant gene expression for anygene of interest including but not limited to selectable markers,scoreable markers, genes for pest tolerance, disease resistance,nutritional enhancements and any other gene of agronomic interest.Examples of constitutive promoters useful for lettuce plant geneexpression include, but are not limited to, the cauliflower mosaic virus(CaMV) P-35S promoter, which confers constitutive, high-level expressionin most plant tissues (see, e.g., Odel et al., 1985), including monocots(see, e.g., Dekeyser et al., 1990; Terada and Shimamoto, 1990); atandemly duplicated version of the CaMV 35S promoter, the enhanced 35Spromoter (P-e35S) the nopaline synthase promoter (An et al., 1988), theoctopine synthase promoter (Fromm et al., 1989); and the figwort mosaicvirus (P-FMV) promoter as described in U.S. Pat. No. 5,378,619 and anenhanced version of the FMV promoter (P-eFMV) where the promotersequence of P-FMV is duplicated in tandem, the cauliflower mosaic virus19S promoter, a sugarcane bacilliform virus promoter, a commelina yellowmottle virus promoter, and other plant DNA virus promoters known toexpress in plant cells.

A variety of plant gene promoters that are regulated in response toenvironmental, hormonal, chemical, and/or developmental signals can beused for expression of an operably linked gene in plant cells, includingpromoters regulated by (1) heat (Callis et al., 1988), (2) light (e.g.,pea rbcS-3A promoter, Kuhlemeier et al., 1989; maize rbcS promoter,Schaffner and Sheen, 1991; or chlorophyll a/b-binding protein promoter,Simpson et al., 1985), (3) hormones, such as abscisic acid (Marcotte etal., 1989), (4) wounding (e.g., wunl, Siebertz et al., 1989); or (5)chemicals such as methyl jasmonate, salicylic acid, or Safener. It mayalso be advantageous to employ organ-specific promoters (e.g., Roshal etal., 1987; Schernthaner et al., 1988; Bustos et al., 1989).

Exemplary nucleic acids which may be introduced to the lettuce lines ofthis invention include, for example, DNA sequences or genes from anotherspecies, or even genes or sequences which originate with or are presentin the same species, but are incorporated into recipient cells bygenetic engineering methods rather than classical reproduction orbreeding techniques. However, the term “exogenous” is also intended torefer to genes that are not normally present in the cell beingtransformed, or perhaps simply not present in the form, structure, etc.,as found in the transforming DNA segment or gene, or genes which arenormally present and that one desires to express in a manner thatdiffers from the natural expression pattern, e.g., to over-express.Thus, the term “exogenous” gene or DNA is intended to refer to any geneor DNA segment that is introduced into a recipient cell, regardless ofwhether a similar gene may already be present in such a cell. The typeof DNA included in the exogenous DNA can include DNA which is alreadypresent in the plant cell, DNA from another plant, DNA from a differentorganism, or a DNA generated externally, such as a DNA sequencecontaining an antisense message of a gene, or a DNA sequence encoding asynthetic or modified version of a gene.

Many hundreds if not thousands of different genes are known and couldpotentially be introduced into a lettuce plant according to theinvention. Non-limiting examples of particular genes and correspondingphenotypes one may choose to introduce into a lettuce plant include oneor more genes for insect tolerance, such as a Bacillus thuringiensis(B.t.) gene, pest tolerance such as genes for fungal disease control,herbicide tolerance such as genes conferring glyphosate tolerance, andgenes for quality improvements such as yield, nutritional enhancements,environmental or stress tolerances, or any desirable changes in plantphysiology, growth, development, morphology or plant product(s). Forexample, structural genes would include any gene that confers insecttolerance including but not limited to a Bacillus insect control proteingene as described in WO 99/31248, herein incorporated by reference inits entirety, U.S. Pat. No. 5,689,052, herein incorporated by referencein its entirety, U.S. Pat. Nos. 5,500,365 and 5,880,275, hereinincorporated by reference it their entirety. In another embodiment, thestructural gene can confer tolerance to the herbicide glyphosate asconferred by genes including, but not limited to Agrobacterium strainCP4 glyphosate resistant EPSPS gene (aroA:CP4) as described in U.S. Pat.No. 5,633,435, herein incorporated by reference in its entirety, orglyphosate oxidoreductase gene (GOX) as described in U.S. Pat. No.5,463,175, herein incorporated by reference in its entirety.

Alternatively, the DNA coding sequences can affect these phenotypes byencoding a non-translatable RNA molecule that causes the targetedinhibition of expression of an endogenous gene, for example viaantisense- or cosuppression-mediated mechanisms (see, for example, Birdet al., 1991). The RNA could also be a catalytic RNA molecule (i.e., aribozyme) engineered to cleave a desired endogenous mRNA product (seefor example, Gibson and Shillito, 1997). Thus, any gene which produces aprotein or mRNA which expresses a phenotype or morphology change ofinterest is useful for the practice of the present invention.

G. Definitions

In the description and tables herein, a number of terms are used. Inorder to provide a clear and consistent understanding of thespecification and claims, the following definitions are provided:

Allele: Any of one or more alternative forms of a gene locus, all ofwhich alleles relate to one trait or characteristic. In a diploid cellor organism, the two alleles of a given gene occupy corresponding locion a pair of homologous chromosomes.

Backcrossing: A process in which a breeder repeatedly crosses hybridprogeny, for example a first generation hybrid (F₁), back to one of theparents of the hybrid progeny. Backcrossing can be used to introduce oneor more single locus conversions from one genetic background intoanother.

Crossing: The mating of two parent plants.

Cross-pollination: Fertilization by the union of two gametes fromdifferent plants.

Diploid: A cell or organism having two sets of chromosomes.

Emasculate: The removal of plant male sex organs or the inactivation ofthe organs with a cytoplasmic or nuclear genetic factor conferring malesterility or a chemical agent.

Enzymes: Molecules which can act as catalysts in biological reactions.

F₁ Hybrid: The first generation progeny of the cross of two nonisogenicplants.

Genotype: The genetic constitution of a cell or organism.

Haploid: A cell or organism having one set of the two sets ofchromosomes in a diploid.

Linkage: A phenomenon wherein alleles on the same chromosome tend tosegregate together more often than expected by chance if theirtransmission was independent.

Marker: A readily detectable phenotype, preferably inherited incodominant fashion (both alleles at a locus in a diploid heterozygoteare readily detectable), with no environmental variance component, i.e.,heritability of 1.

Phenotype: The detectable characteristics of a cell or organism, whichcharacteristics are the manifestation of gene expression.

Quantitative Trait Loci (QTL): Quantitative trait loci (QTL) refer togenetic loci that control to some degree numerically representabletraits that are usually continuously distributed.

Regeneration: The development of a plant from tissue culture.

Royal Horticultural Society (RHS) color chart value: The RHS color chartis a standardized reference which allows accurate identification of anycolor. A color's designation on the chart describes its hue, brightnessand saturation. A color is precisely named by the RHS color chart byidentifying the group name, sheet number and letter, e.g., Yellow-OrangeGroup 19A or Red Group 41B.

Self-pollination: The transfer of pollen from the anther to the stigmaof the same plant.

Single Locus Converted (Conversion) Plant: Plants which are developed bya plant breeding technique called backcrossing, wherein essentially allof the desired morphological and physiological characteristics of alettuce variety are recovered in addition to the characteristics of thesingle locus transferred into the variety via the backcrossing techniqueand/or by genetic transformation.

Substantially Equivalent: A characteristic that, when compared, does notshow a statistically significant difference (e.g., p=0.05) from themean.

Tetraploid: A cell or organism having four sets of chromosomes.

Tissue Culture: A composition comprising isolated cells of the same or adifferent type or a collection of such cells organized into parts of aplant.

Transgene: A genetic locus comprising a sequence which has beenintroduced into the genome of a lettuce plant by transformation.

Triploid: A cell or organism having three sets of chromosomes.

H. Deposit Information

A deposit of lettuce line RX06462133, disclosed above and recited in theclaims, has been made with the American Type Culture Collection (ATCC),10801 University Blvd., Manassas, Va. 20110-2209. The date of depositwas Feb. 26, 2010. Upon issuance of a patent, all restrictions upon thedeposit will be removed, and the deposit is intended to meet all of therequirements of 37 C.F.R. §1.801-1.809. The accession number for thosedeposited seeds of lettuce line RX06462133 is ATCC Accession No.PTA-10689. The deposit will be maintained in the depository for a periodof 30 years, or 5 years after the last request, or for the effectivelife of the patent, whichever is longer, and will be replaced ifnecessary during that period.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

All references cited herein are hereby expressly incorporated herein byreference.

REFERENCES

The following references, to the extent that they provide exemplaryprocedural or other details supplementary to those set forth herein, arespecifically incorporated herein by reference:

-   U.S. Pat. No. 5,349,124-   U.S. Pat. No. 5,378,619-   U.S. Pat. No. 5,463,175-   U.S. Pat. No. 5,500,365-   U.S. Pat. No. 5,563,055-   U.S. Pat. No. 5,633,435-   U.S. Pat. No. 5,689,052-   U.S. Pat. No. 5,880,275-   An et al., Plant Physiol., 88:547, 1988.-   Bird et al., Biotech. Gen. Engin. Rev., 9:207, 1991.-   Bustos et al., Plant Cell, 1:839, 1989.-   Callis et al., Plant Physiol., 88:965, 1988.-   Choi et al., Plant Cell Rep., 13: 344-348, 1994.-   Chupeau et al., Bio/Tech., 7:503-508, 1989.-   Dekeyser et al., Plant Cell, 2:591, 1990.-   Elliott et al., Plant Cell Rep., 18:707-714, 2004.-   Ellul et al., Theor. Appl. Genet., 107:462-469, 2003.-   EP 534 858-   Fraley et al., Bio/Technology, 3:629-635, 1985.-   Fromm et al., Nature, 312:791-793, 1986.-   Fromm et al., Plant Cell, 1:977, 1989.-   Gibson and Shillito, Mol. Biotech., 7:125,1997-   Klee et al., Bio-Technology, 3(7):637-642, 1985.-   Kuhlemeier et al., Plant Cell, 1:471, 1989.-   Marcotte et al., Nature, 335:454, 1988.-   Marcotte et al., Plant Cell, 1:969, 1989.-   Molinier et al., Plant Cell Rep., 21:251-256, 2002.-   Odel et al., Nature, 313:810, 1985.-   Omirulleh et al., Plant Mol. Biol., 21(3):415-428, 1993.-   Pang et al., The Plant J., 9, 899-909, 1996.-   Potrykus et al., Mol. Gen. Genet., 199:183-188, 1985.-   Roshal et al., EMBO J., 6:1155, 1987.-   Ryder, In: Breeding Vegetable Crops, AVI Pub., Westport, Conn.,    433-474, 1986.-   Schaffner and Sheen, Plant Cell, 3:997, 1991.-   Schernthaner et al., EMBO J., 7:1249, 1988.-   Siebertz et al., Plant Cell, 1:961, 1989.-   Simpson et al., EMBO J., 4:2723, 1985.-   Terada and Shimamoto, Mol. Gen. Genet., 220:389, 1990.-   Uchimiya et al., Mol. Gen. Genet., 204:204, 1986.-   Wang et al., Science, 280:1077-1082, 1998.-   Williams et al., Nucleic Acids Res., 1 8:6531-6535, 1990.-   WO 99/31248

1. A seed of lettuce line RX06462133, a sample of seed of said linehaving been deposited under ATCC Accession Number PTA-10689.
 2. A plantgrown from the seed of claim
 1. 3. A plant part of the plant of claim 2.4. The plant part of claim 3, wherein said part is selected from thegroup consisting of a pollen, an ovule and a cell.
 5. A lettuce plant,or a part thereof, having all the physiological and morphologicalcharacteristics of the lettuce plant of claim
 2. 6. A method ofproducing lettuce seed, comprising crossing the plant of claim 2 with asecond lettuce plant.
 7. The method of claim 6, wherein the plant oflettuce line RX06462133 is the female parent.
 8. An F1 hybrid seedproduced by the method of claim
 6. 9. An F1 hybrid plant produced bygrowing the seed of claim
 8. 10. A progeny plant of the plant of claim 2that comprises all of the physiological and morphologicalcharacteristics of lettuce line RX06462133, a sample of seed of saidline having been deposited under ATCC Accession Number PTA-10689.
 11. Aseed that produces the plant of claim
 10. 12. A method of producinglettuce comprising: (a) obtaining the plant of claim 2, wherein theplant has been cultivated to maturity, and (b) collecting lettuce fromthe plant.
 13. A tissue culture of regenerable cells of lettuce lineRX06462133, a sample of seed of said line having been deposited underATCC Accession Number PTA-10689.
 14. The tissue culture according toclaim 13, comprising cells or protoplasts from a plant part selectedfrom the group consisting of embryos, meristems, cotyledons, pollen,leaves, anthers, roots, root tips, pistil, flower, seed and stalks. 15.A lettuce plant regenerated from the tissue culture of claim 13, whereinthe regenerated plant expresses all of the physiological andmorphological characteristics of lettuce line RX06462133, a sample ofseed of said line having been deposited under ATCC Accession NumberPTA-10689.
 16. A method for producing a seed of a lineRX06462133-derived lettuce plant comprising the steps of: (a) crossing alettuce plant of line RX06462133, a sample of seed of said line havingbeen deposited under ATCC Accession Number PTA-10689, with a secondlettuce plant; and (b) allowing seed of a RX06462133-derived lettuceplant to form.
 17. The method of claim 16, further comprising the stepsof: (c) crossing a plant grown from said RX06462133-derived lettuce seedwith itself or a second lettuce plant to yield additionalRX06462133-derived lettuce seed; (d) growing said additionalRX06462133-derived lettuce seed of step (c) to yield additionalRX06462133-derived lettuce plants; and (e) repeating the crossing andgrowing steps of (c) and (d) to generate further RX06462133-derivedlettuce plants.
 18. A method of vegetatively propagating a plant oflettuce line RX06462133 comprising the steps of: (a) collecting tissuecapable of being propagated from a plant of lettuce line RX06462133, asample of seed of said line having been deposited under ATCC AccessionNumber PTA-10689; (b) cultivating said tissue to obtain proliferatedshoots; and (c) rooting said proliferated shoots to obtain rootedplantlets.
 19. The method of claim 18, further comprising growing plantsfrom said rooted plantlets.
 20. A method of introducing a desired traitinto lettuce line RX06462133 comprising: (a) crossing a plant of lineRX06462133, a sample of seed of said line having been deposited underATCC Accession Number PTA-10689, with a second lettuce plant thatcomprises a desired trait to produce F1 progeny; (b) selecting an F1progeny that comprises the desired trait; (c) crossing the selected F1progeny with a plant of line RX06462133, to produce backcross progeny;(d) selecting backcross progeny comprising the desired trait and thephysiological and morphological characteristic of lettuce lineRX06462133; and (e) repeating steps (c) and (d) three or more times insuccession to produce selected fourth or higher backcross progeny thatcomprise the desired trait and all of the physiological andmorphological characteristics of lettuce line RX06462133 when grown inthe same environmental conditions.
 21. A lettuce plant produced by themethod of claim
 20. 22. A method of producing a plant of lettuce lineRX06462133, a sample of seed of said line having been deposited underATCC Accession Number PTA-10689, comprising an added desired trait, themethod comprising introducing a transgene conferring the desired traitinto a plant of lettuce line RX06462133.